Does Benadryl Make Cats Sleep?

This cat's nap was brought to you by Benadryl.
i Hemera Technologies/ Images

If you've ever taken Benadryl for allergies or itching, you know it can make you sleepy. If you're planning on taking Felix on a road trip, you may want to sedate him so he naps away the ride. Benadryl may help him snooze.

What Is Benadryl?

Benadryl is a the brand name for the antihistamine drug diphenhydramine hydrochloride. Antihistamines are typically used to calm allergy symptoms like sneezing and watery eyes. Benadryl has a sedative effect in both humans and cats that makes both of you sleepy when you take it. If you need Felix to be sleepy, like keeping him calm on a plane, Benadryl is safe for him to take. Always consult with a qualified veterinarian before giving him any medicine to make sure the dosage is correct and it won't interfere with other meds he may be taking. Typically you'll give the cat a dose that's a fraction of human dosage -- half a pill or less.

Nap Time

In cats, the sedative effect of diphenhydramine lasts for eight to 12 hours. Unlike sedatives such as diazapam, antihistamines don't cause Felix to be disoriented and confused. If you're using it to calm him down during traveling, make sure his carrier is comfortable and familiar. Using a soothing voice, talk to him to keep your buddy calm until he falls asleep.

Correct Dosage

Dosage depends on your cat's size, age and health. Typically, he'll need about 0.5 mg to 2mg per pound every 8 to 12 hours. If Felix is a little monster, he'll need more medicine than a smaller cat for to have the same effect. Take him to the vet before you give it to him to determine what a safe dosage is for him.


Pregnant cats shouldn't take Benadryl; it won't work and it could cause complications for the pregnancy. If Felix has prostate issues, eye problems, heart problems or thyroid issues, or if he is already taking a drug that contains dyphenhydramine, he shouldn't take Benadryl. When he takes it from time to time, drowsiness is probably the only side effect he'll experience. If he takes it regularly over a long period he could experience side effects such as an upset tummy, stinky breath, trouble using the bathroom, vision problems and hormone imbalance. If you see Felix starting to have any of these reactions to the medicine, he should stop taking it and visit his vet.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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